Data Zone
Justification of Red List category
This widespread species declined historically in the southern parts of its range, primarily owing to the destruction and degradation of its preferred woodland habitat, predation by introduced foxes and interactions with habitat loss, however most of these declines occurred prior to the past three generations (32 years). The species remains common in northern Australia, including in urban areas where there is no evidence of declines despite depredation from feral and domestic cats and dogs. As there is no evidence to suggest the species has undergone a moderately rapid population decline over three generations, and the species’s range and population are both large and do not approach any of the thresholds for classification as Vulnerable, it has therefore been downlisted to Least Concern.
Population justification
The total Australian population has separately been estimated at 15,000 individuals, and to almost certainly exceed 10,000 mature individuals (Garnett et al. 2011). The population is therefore placed in the band 10,000-15,000 mature individuals.
Trend justification
This widespread species declined historically in the southern parts of its range, primarily owing to the destruction and degradation of its preferred woodland habitat, predation by introduced foxes and interactions with habitat loss, however most of these declines occurred prior to the past three generations (32 years). The species remains common in northern Australia, including in urban areas where there is no evidence of declines despite depredation from feral and domestic cats and dogs. It is therefore suspected to have undergone a slow overall population decline during the past three generations.
Burhinus grallarius has been recorded from all but the most arid parts of mainland Australia, and many offshore islands. A tiny breeding population is also found in southern New Guinea (Papua, formerly Irian Jaya, Indonesia, and Papua New Guinea). In Australia, it is now largely absent south and east of the Great Dividing Range, and is scarce elsewhere in southern Australia. Historic declines led to its disappearance from 90% of its mainland range in South Australia (D. Harley in litt. 2006), however it remains common in northern Australia and on many continental islands, even within towns (S. Garnett in litt. 2006, 2011), although it has declined in southern Queensland. The total Australian population has been estimated at 15,000 individuals (Watkins 1993), and in 2010 the total population was estimated to almost certainly exceed 10,000 mature individuals (S. Garnett. in litt. 2011).
It is a resident of open forest and woodland, preferring a scattering of fallen timber and ground carpeted with dead leaves. The species feeds nocturnally on insects taken from the ground and is thought to forage primarily in open country, including paddocks and stubble in agricultural areas (D. Watson in litt. 2006, D. Harley in litt. 2007) (in urban coastal areas birds forage on ovals, mudflats and saltmarsh) (C. Price in litt. 2007). Pairs occupy stable territories and display long-term site fidelity (D. Harley in litt. 2007). During the non-breeding season, individuals may gather in small flocks (D. Harley in litt. 2007).
Its decline in its southern range has been attributed to predation by the introduced Red Fox Vulpes vulpes, habitat clearance for agriculture and urban development, habitat degradation by pastoralism, and removal of fallen timber from habitat remnants. Other threats include poisoning from pesticides or insecticides and in urban areas, road mortalities and predation by cats and domestic dogs (T. Holmes in litt. 2006, D. Harley in litt. 2007). Population monitoring in south-eastern South Australia suggests that poor nesting success and a lack of juvenile recruitment are significant factors limiting populations (D. Harley in litt. 2007). Nestling mortality, probably owing to predation, appears to be the main cause of nesting failure (D. Harley in litt. 2007). Hunting of the species is illegal.
Conservation Actions Underway
Fox control has been trialled in Victoria in an attempt to reduce predation of adults and chicks (D. Robinson and G. Johnson in litt. 2006, D. Harley in litt. 2007). A post-graduate study into the demography and ecology of the species in New South Wales and Victoria has been completed (E. Tack in litt. 2006). A number of conservation projects for the species have been implemented in south-eastern Australia, in Victoria (3), South Australia (2) and New South Wales (4) (D. Harley in litt. 2006, D. Harley in litt. 2007, C. Price in litt. 2007). Habitat requirements of the species in different areas are becoming better understood. Community involvement and support for projects are increasing, and the profile of the species has been raised in many areas (C. Price in litt. 2007). Molecular studies at the Australian Museum were underway and expected to be completed in 2007, with the aim of clarifying whether genetic differentiation is evident between populations in northern and southern Australia (D. Harley in litt. 2007, C. Price in litt. 2007).
54-59cm. A slim, long-legged and long-tailed thick-knee. Has a grey and rufous morph. Cryptic plumage typical of the genus. Has long wings with rather broad, square, fingered tips. Large pale eyes in its big round head with a relatively fine dark bill. Similar spp. Generally unmistakeable but could be confused with beach thick-knee Esacus magnirostris which has a much larger bill and strictly inhabits coastal areas. Could also be confused with nightjars Caprimulgus but these have a very different flight pattern and are considerably smaller in size. Voice Nocturnal wailing call.
Text account compilers
Benstead, P., Bird, J., Butchart, S., Garnett, S., Symes, A., Taylor, J.
Contributors
Weston, M., Garnett, S., Ford, H., Harley, D., Holmes, T., Carter, A., Christidis, L., Price, C., Tack, E., Woinarski, J.
Recommended citation
BirdLife International (2024) Species factsheet: Bush Thick-knee Burhinus grallarius. Downloaded from
https://datazone.birdlife.org/species/factsheet/bush-thick-knee-burhinus-grallarius on 22/11/2024.
Recommended citation for factsheets for more than one species: BirdLife International (2024) IUCN Red List for birds. Downloaded from
https://datazone.birdlife.org/species/search on 22/11/2024.